Thermal exploitation of fruit tree pruning wastes in a novel conical spouted bed combustor

• Conical spouted bed combustor is feasible for thermal exploitation of fruit tree wastes.
• Gas temperature increases minimum spouting and minimum dilute spouted bed velocities.
• Minimum spouting and minimum dilute spouted bed velocities increase with particle size.
• Bed temperature decreases with radial and axial positions in the combustor.

In order to determine the optimum operation conditions for thermal exploitation of fruit-tree pruning wastes in conical spouted bed combustors, operation maps for gas–solid flow regimes have been obtained from the experimental hydrodynamic study of beds of inert material (sand) in conical spouted bed contactors at high temperatures. To this end, minimum spouting and minimum dilute spouting (jet spouted bed) velocities and maximum bed pressure drop have been obtained for different systems. The effects of particle size and gas inlet temperature has been also studied. Combustion of fruit-tree pruning wastes has been successfully carried out in batch mode in a conical spouted bed combustor, with high combustion efficiencies, for gas inlet temperatures from 350 to 550 °C. Radial and axial temperature profiles have been measured both in uniform beds of inert material and also in beds composed of mixtures of sand and combusting wastes.